Shuttle Loop is Meta Knight's up special attack in the Super Smash Bros. series, first appearing in Super Smash Bros. Brawl. It's a recovery move that'll cause Meta Knight to thrust his sword upwards and jump higher than normal. It has decent speed and will knock enemies relatively far. If an opponent has a pretty high percentage of damage, then this attack has the potential of quickly KO'ing them.
Right after shooting himself upwards, he'll bring out his cape and start to glide automatically. This can be discontinued if you desire.